Vacuum-type electrical device

ABSTRACT

A vacuum interrupter comprises a hollow cylindrical housing having openings at opposite ends and is made of vacuumtight ceramic. An integrally formed shoulder is provided inside the housing near each opening. A thin metallic end seal having a central opening abuts each shoulder and is sealed in place thereon. A stationary electrode extends from the exterior of the housing through the central opening in one end seal into the interior of the housing and is sealed to its end seal. A vacuum pinch-off tube is provided in the said one seal. A tubular metallic arc shield extends through the central opening in the other end seal into the interior of the housing, surrounds a portion of the stationary electrode and is sealed to its end seal. The tubular shield is immobilized by an external bead thereon which engages the inner wall of the housing. A movable electrode for cooperation with the stationary electrode extends into the housing through the tubular arc shield. A flexible bellows seals the space between the tubular arc shield and the movable electrode. Each electrode is provided with a disk-type arc shield to confine arc products within the tubular shield and to protect the bellows. Metal end or mounting plates are clamped against respective ends of the housing by detachable clamping means which engage an exterior flange on the housing. One of the end plates is electrically connected to its associated stationary contact.

United States Patent 1 72] inventors Herbert M. Pflanz Westwood; William E. Harper, Walpole, both of Mass. [21] Appl. No. 91,001 [22] Filed Nov. 19, 1970 [45] Patented Dec. 7, 1971 [73] Assignee Allis-Chalmers Manufacturing Company Milwaukee, Wis.

[54] VACUUM-TYPE ELECTRICAL DEVICE 8 Claims 1 Drawing Fig.

Primary Examiner-Robert S. Macon Attorneys-Thomas F. Kirby, Robert B. Benson and Lee H.

Kaiser ABSTRACT: A vacuum interrupter comprises a hollow cylindrical housing having openings at opposite ends and is made of vacuumtight ceramic. An integrally formed shoulder is provided inside the housing near each opening. A thin metallic end seal having a central opening abuts each shoulder and is sealed in place thereon. A stationary electrode extends from the exterior of the housing through the central opening in one end seal into the interior of the housing and is sealed to its end seal. A vacuum pinch-off tube is provided in the said one seal.

A tubular metallic arc shield extends through the central opening in the other end seal into the interior of the housing, surrounds a portion of the stationary electrode and is sealed to its end seal. The tubular shield is immobilized by an external bead thereon which engages the inner wall of the housing. A movable electrode for cooperation with the stationary elec trode extends into the housing through the tubular arc shield. A flexible bellows seals the space between the tubular arc shield and the movable electrode. Each electrode is provided with a disk-type arc shield to confine are products within the tubular shield and to protect the bellows. Metal end or mounting plates are clamped against respective ends of the housing by detachable clamping means which engage an exterior flange on the housing. One of the end plates is electrically connected to its associated stationary contact.

VACUUM-TYPE ELECTRICAL DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to vacuum-type electrical devices, such as vacuum interrupters. More particularly, it relates such devices suitable for outdoor service and which can withstand high cantilever and axial forces.

2. Description of the Prior Art Heretofore, some vacuum interrupters comprised cylindrical glass or ceramic envelopes which, because of their mechanical fragility, had to be placed within separate protective housings, usually made of porcelain, plastic, or other insulating material. The additional components and labor required for this increased interrupter costs. U.S. Pat. No. 2,870,298 issued Jan. 20, 1959, to H. H. Schwager for Encapsulated Vacuum Insulated'Circuit Breaker illustrates one prior art SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a vacuum-type electrical device, such as a vacuum circuit interrupter, which comprises an envelope made of vacuumtight insulating material, such as high-grade ceramic, and having a chamber therein with at least onegopening communicating between the chamber and the exterior of the envelope. A shoulder is provided in the wall of the chamber. A sealing member abuts the shoulder and is sealed'in place thereagainst. The sealing member is fabricated of thin metal, such as Kovar metal, which has thermal expansion characteristics similar to those of the envelope. The sealing member is provided with an opening for accommodating conductive means, including an electrode, which extends into the envelope and the sealing means is sealed to such means. A protective end plate, also usable for mounting purposes or electrical connection or both, is provided at the exterior of the envelope near the opening therein and is secured by clamping means, preferably removable, which engage the end plate and an integrally formed flange means provided on the exterior of the envelope. In one aspect of the invention the conductive means comprises an electrode. In another aspect, the conductive means comprises a shield, a bellows and a movable electrode. The sealing member accommodates and is sealed to the shield and the bellows is connected between the shield and the movable electrode. In a preferred embodiment where the envelope houses both a stationary and movable electrode, each electrode is provided with a disk-type shield to confine are products within the tubular shield, thereby protecting the bellows and build-up of are products on the envelope wall. In a preferred embodiment, a portion of the interior of the housing is of smaller diameter than the rest to engage with a flange formed on the exterior surface of the tubular housing to help hold the latter rigidly in place.

OBJECTS OF THE INVENTION It is an object of the invention to provide improved vacuumtype electrical devices, especially vacuum interrupters and switches.

Another object is to provide such devices which, when mounted in place, can withstand high cantilever and axial forces and have a strong, vacuumtight envelope suitable for outdoor service.

Another object is to provide such devices wherein the vacuum seals are recessed in the envelope and covered by other components for protection against physical damage and which are subjected to none of the mechanical forces involved in physically supporting the device in a field installation.

Another object is to provide such devices wherein the housing or envelope is fabricated of strong vacuumtight material which bears all mechanical forces involved in supporting the devices.

Another object is to provide improved vacuum interrupters which are mechanically stronger than prior art devices of comparable size but require fewer components and less labor to manufacture.

Another object is to provide vacuum interrupters of the aforesaid character which are designed so that subassemblies are conveniently and economically fabricated and readily assembled into final assemblies.

Other objects and advantages of the invention will hereinafter appear.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustrates a preferred embodiment of the invention but it is to be understood that the embodiment illustrated is susceptible of modifications with respect to details thereof without departing from the scope of the appended claims.

In the drawing the single FIGURE is a cross-sectional view of a vacuum interrupter in accordance with the present invention. 7

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, there is shown a vacuum-type circuit interrupter in accordance with the present invention which is understood'to be used in high voltage electrical circuits to interrupt relatively high amperage currents. The interrupter comprises an envelope 10 made of vacuumtight, heat resistant, electrical insulating material such as high grade ceramic. Envelope 10 is in the'form of a cylinder having a cylindrical chamber 12 therein which is provided with openings 14 and 16, respectively, at opposite ends which communicate between the chamber and the exterior of the envelope. If preferred, the exterior of envelope 10 may be provided with skirts or sheds 1810 increase voltage creep distance on its exterior. Envelope 10 is provided with annular shoulders or ledges 20 and 22 on the wall of chamber 12 near the openings 14 and 16, respectively, which preferably are integrally formed in envelope l0. Envelope 10 is further provided with flange means 24 and 26 on the exterior thereof near the openings 14 and 16, respectively, which preferably are integrally formed with envelope l0 and are annular in shape. Envelope 10 is also constructed so that a portion of chamber 12 near opening 16 is of smaller diameter than the rest of the chamber to provide a supporting means, as hereinafter described.

Electrically conductive means including a pair of relatively movable cooperating electrodes in the form of a stationary contact rod 28 and a movable contact rod 30 extend into chamber 12 through the openings 14 and 16, respectively, in envelope 10. The space between envelope 10 and stationary rod 28 is sealed by a vacuumtight sealing member 32 which is in the form of a circular, disk having a central opening 34 for accommodating the stationary contact rod. Sealing member 32, which also aids in supporting rod 28, made of thin metal having thermal expansion and contraction characteristics similar to the ceramic material of which envelope I0 is made, such as Kovar metal or the like, and is relatively fragile. Sealing member 32 is disk-shaped and preferably flanged around its outer periphery and around its opening 34 to provide a larger surface for attaching it to associated components. Sealing member 32 rests on or abuts against shoulder 20 and is sealed to the wall of chamber 12 by suitable sealing means 36, preferably brazing material which adheres to the sealing member and to a metallized coating 38 provided on shoulder 20 and the chamber wall. Sealing member 32 is welded or brazed to stationary contact rod 28 as at 40. Sealing member 32 is provided with an opening 41 in which a vacuum pinchoff tube 43 is welded.

End plate means 42 are provided to close ofi" the upper opening 14 in envelope 10 thereby protecting fragile sealing member 32 from accidental physical damage; to provide physical support for and an electrical connection to stationary contact 28; and to provide a strong means for and physically or mechanically mounting the circuit interrupter when in use. End plate means 42 comprise a metal end plate 44, preferably relatively fiat and circular, which bears against the flat end surface of envelope l surrounding opening 14. End plate means 42 further comprise a metal contacting block 46 which is welded to or integrally formed with end plate 44 and is provided with a hole 48 into which the outer end of stationary contact 28 extends. Another threaded opening 50 transversely intersects hole 48 and accommodates a threaded set screw 52 which gives physical support to and makes a sound electrical connection between block 46 and rod 28. End plate 44 is secured against envelope by clamping means 53 including a plurality of L-shaped removable clamps 55 which are secured to the end plate as by bolts 57 and engage the flange means 24 on the exterior of envelope 10. End plate 44 is provided with means, such as a hole 45, which facilitates attachment of the conductor thereto.

End plate means 54 are provided to close off the lower opening 16 in envelope 10 thereby protecting a sealing member 56, a tubular metal shield means 58, and a bellows or flexible sealing means 60 disposed in opening 16 in envelope 10. End plate means 54 comprises a metal end plate 62, preferably flat and circular, which bears against the flat end surface of envelope l0 surrounding opening 16. End plate 62 is provided with a central opening 64 which accommodates movable contact rod 30. End plate 62 is secured against enveloped 10- by clamping means 66 comprising clamps 68 which engage flange 26 of envelope [0 and bolts 70, similar to the clamps 55 and bolts 57 hereinbefore described.

Tubular shield means 58 is in the form of a hollow metal cylinder and is provided with an annular projection 72 which fits snugly against the wall of the narrowed portion of chamber 12 to help support the shield against dislocation. Sealing 56 is similar in construction to scaling member 32, hereinbefore described, and is seated against shoulder 22 and welded to a metallized coating 59 on envelope l0 and to shield 58, thereby providing additional support for the shield. Bellows 60, tubular in form, are located within shield 58 and are welded at one end to the shield and at the other end to movable contact rod 30.

Stationary contact rod 28 is provided with a disk-type metallic shield 73 which is rigidly secured thereon as by welding near the end of tubular shield 58. Shield 73 is of a diameter greater than that of tubular shield 58 so as to prevent direct exposure of sealing member 32 to are products emanating from the region of the separable ends of the contact rods 28 and 30.

Movable contact rod 30 is provided with a disk-type metallic shield 74 which is rigidly secured thereon as by welding and is located inside tubular shield 58 to protect bellows 60 from direct exposure to are products.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a vacuum-type electrical device,

an envelope of insulating material having a chamber therein and at least one opening communicating between the chamber and the exterior of said envelope,

a shoulder on the wall of said chamber,

a sealing member abutting said shoulder and having an opening therethrough,

electrically conductive means extending through said openings in said envelope and in said sealing member into said chamber, said electrically conductive means sealed to said sealing member,

end plate means including an end plate abutting said housing adjacentsaid o ening in said envelope, flange means integr ly formed on the exterior of said envelope,

and clamping means engaging said flange means and said end plate to secure the latter in place.

2. A device according to claim 1 wherein said electrically conductive means comprises a stationary contact rod and said sealing member is sealed to said stationary contact rod.

3. A device according to'claim 1 wherein said electrically conductive means comprises a tubular shield, a movable contact rod extending through said tubular shield and flexible sealing means connected between said tubular shield and said movable contact rod, and wherein said sealing member is sealed to said tubular shield.

4. In a vacuum-type circuit interrupter,

an envelope of vacuumtight insulating material having a chamber therein and first and second spaced apart openings communicating between said chamber and the exterior of said envelope,

first and second shoulders on the wall of said chamber near said first and second openings, respectively,

a stationary contact rod and a movable contact rod extending into said chamber through said first and second openings, respectively, in said envelope,

a first metallic sealing member abutting said first shoulde and sealing the space between said stationary contact rod and the wall of said chamber,

a tubular shield surrounding a portion of said movable contact rod,

a second metallic sealing member abutting said second shoulder and sealing the space between said tubular shield and the wall of said chamber,

flexible sealing means surrounding a portion of said movable contact rod and sealing the space between said tubular shield and said movable contact rod,

first and second flanges on the exterior of said envelope near said first and second openings, respectively,

and first and second clamping means engageable with said first and second flanges, respectively, and said first and second end plate means, respectively, to secure the latter in place on said envelope.

5. An interrupter according to claim 4 wherein said chamber is cylindrical and said shoulders are integrally formed in said envelope and are formed by annular openings of greater diameter than adjacent portions of said chamber.

6. An interrupter according to claim 5 wherein one portion of said chamber is of smaller diameter than the remainder, and wherein said tubular shield has projecting means thereon which engage the wall of said chamber at said portion of smaller diameter.

7. An interrupter according to claim 6 wherein said first end plate means comprises an end plate which bears against a flat portion of said envelope surrounding said first opening and further comprises a contacting block secured to said end plate and to said stationary electrode.

8. An interrupter according to claim 7 including first and second shields on said stationary and movable contact rods, respectively, to protect said sealing members from direct exposure to are products.

t w n: 

1. In a vacuum-type electrical device, an envelope of insulating material having a chamber therein and at least one opening communicating between the chamber and the exterior of said envelope, a shoulder on the wall of said chamber, a sealing member abutting said shoulder and having an opening therethrough, electrically conductive means extending through said openings in said envelope and in said sealing member into said chamber, said electrically conductive means sealed to said sealing member, end plate means including an end plate abutting said housing adjacent said opening in said envelope, flange means integrally formed on the exterior of said envelope, and clamping means engaging said flange means and said end plate to secure the latter in place.
 2. A device according to claim 1 wherein said electrically conductive means comprises a stationary contact rod and said sealing member is sealed to said stationary contact rod.
 3. A device according to claim 1 wherein said electrically conductive means comprises a tubular shield, a movable contact rod extending through said tubular shield and flexible sealing means connected between said tubular shield and said movable contact rod, and wherein said sealing member is sealed to said tubular shield.
 4. In a vacuum-type circuit interrupter, an envelope of vacuumtight insulating material having a chamber therein and first and second spaced apart openings communicating between said chamber and the exterior of said envelope, first and second shoulders on the wall of said chamber near said first and second openings, respectively, a stationary contact rod and a movable contact rod extending into said chamber through said first and second openings, respectively, in said envelope, a first metallic sealing member abutting said first shoulder and sealing the space between said stationary contact rod and the wall of said chamber, a tubular shield surrounding a portion of said movable contact rod, a second metallic sealing member abutting said second shoulder and sealing the space between said tubular shield and the wall of said chamber, flexible sealing means surrounding a portion of said movable contact rod and sealing the space between said tubular shield and said movable contact rod, first and second flanges on the exterior of said envelope near said first and second openings, respectively, and first and second clamping means engageable with said first and second flanges, respectively, and said first and second end plate means, respectively, to secure the latter in place on said envelope.
 5. An interrupter according to claim 4 wherein said chamber is cylindrical and said shoulders are integrally formed in said envelope and are formed by annular openings of greater diameter than adjacent portions of said chamber.
 6. An interrupter according to claim 5 wherein one poRtion of said chamber is of smaller diameter than the remainder, and wherein said tubular shield has projecting means thereon which engage the wall of said chamber at said portion of smaller diameter.
 7. An interrupter according to claim 6 wherein said first end plate means comprises an end plate which bears against a flat portion of said envelope surrounding said first opening and further comprises a contacting block secured to said end plate and to said stationary electrode.
 8. An interrupter according to claim 7 including first and second shields on said stationary and movable contact rods, respectively, to protect said sealing members from direct exposure to arc products. 